Secondary hydriding can take place during a loss-of-coolant accident event after the ballooning and burst of the zirconium alloy cladding. The oxidation and hydrogen uptake in the ballooned section can produce the weakest segment of the rod. This phenomenon was investigated in the past mainly for Zircaloy-4 cladding. We investigated the effect of secondary hydriding in VVER reactors with E110 and E110G alloys. A high-temperature facility was built to carry out high-temperature treatment of fuel cladding samples. The burst of tubes was reached with inner pressurization at 750 and 800°C. After burst the samples were oxidized in the same furnace for different periods and at different temperatures. The oxidized samples were tested in a tensile test machine with four-point bending tests. The microstructure of the samples was analyzed by optical and scanning electron microscopy. The hydrogen content of the cladding was measured by heat extraction, prompt gamma activation analyses, and neutron radiography methods. The experiments indicated that the ballooned section after oxidation became the weakest segment of the VVER fuel. According to the mechanical testing, the cladding samples were brittle even after a short oxidation time (200 s at 1,000°C) without any sign of ductile behavior. The comparison of E110 and E110G samples showed that the E110 tubes lost their load-bearing capability or even integrity much earlier than the E110G samples treated under similar conditions.